Patent GB-1338584-A (GB)
Title: Hydraulically powered pump having a precompression function
IPC: F04B9/08
Filed: 1970-12-18
Abstract: 1338584 Hydraulic reciprocating pumps and motors HALLIBURTON CO 18 Dec 1970 [19 Dec 1969] 60219/70 Heading F1A A Triplex pump 20 comprises three power cylinder pumping unit assemblies 1-40, 2-40 and 3-40 in communication via valves with a common suction conduit and a common discharge conduit and each controlled by a pair of power circuit I and D sleeve valve assemblies CV (Fig. 4) to each consecutively perform suction, precompression and discharge stages with simultaneous performance of different ones of said stages in different ones of said pumping units, the I and D sleeve valves forming the power circuit valve assembly controlling pressurized power fluid from a power circuit pump 210 to the 1 to 3-40 power cylinder assemblies via acommon chamber 82 of the appropriate two sleeve (I, D) valve, and exhausting to a power circuit reservoir 208, the 1-3 CV sleeve valve assemblies themselves being controlled by circuit conditioning valves A, B and C which in turn are controlled by 1 to 3-FP (i.e. forward position) valves trip operated by cams 58 on the pistons of the 1 to 3-40 power cylinders at the end of their effective stroke functions, the control circuit pressure being supplied by a control circuit pump 226 and exhausted to a control circuit reservoir 228 the control circuit conditioning valves A, B and C being prevented from drifting after shifting by double cylinder lock valves DCL-A to C respectively. The arrangement is such that each pumping unit 1 to 3-40 operates on a suction, precompression, discharge cycle out of phase with the cycles of the other pumping units whereby all thee pumping units perform only one (but each different) function during any one phase of the pumping cycle, the pump operating with constant pressure flow of power fluid into and out of the power end of the pump. Operation:- 1st PHASE OF PUMPING CYCLE:- In the 1st phase of the pumping cycle the numbers 1-40, 2-40 and 3-40 power cylinder assemblies undergo suction, discharge and precompression functions respectively as follows:-  1. The sleeve valve 2I of the 2-CV control valve assembly is pressurized at port 21-A of its chamber A via a control circuit conditioning valve A at 324 from a control circuit pump 226 and is thus downwardly moved from its upper i.e. closed position to its lower i.e. open position 322 to pressurize a central control chamber 82 of the 2-CV valve assembly via the power circuit pump 210 to effect the discharge stroke in the 2-40 power cylinder, this downward movement discharging control fluid from its chamber B via port 2 I-B to port 1 I-B of the sleeve valve 1 I or the 1-CV control valve assembly thereby urging the 1 I sleeve valve to its upper closed position, the control fluid in the A i.e. upper chamber of the 1 I sleeve valve being displaced i.e. exhausted to a control circuit reservoir 228 via the 1 I-A port and the control conditioning valve C at 330, the valve C being considered in a 'tanked' condition when connected as such to the reservoir 228. During the time the 1 I sleeve valve is being closed in response to opening of the 2 I sleeve valve, the position of the 1D valve is being conditioned to be altered, the circuit pressure at port 2 I-A of the 2 I valve being simultaneously connected via duct 150 (Fig.3) to port 1D-A of the 1 CV valve assembly but prevented from entering the chamber A of the ID sleeve valve to operate this valve by means of a blocking pilot operated valve PO-1 which remains closed until the 1 I sleeve valve reaches its upper closed position to uncover a port 1 I-C to provide pilot pressure at port 1-168 (Figs. 7 and 7A) to open the blocking pilot valve PO-1 via its pilot piston 282 which operates to open in two stages to provide two-stage opening of the connected 1D valve so as to prevent its connected power cylinder decompressing at too great a rate to prevent shock forces on the pump structure, the 1D sleeve valve thus being moved from its upper closed to its lower open position to exhaust the central chamber 82 of the 1-CV valve assembly to the power circuit reservoir 208, to effect the suction stroke in the 1-40 power cylinder, the delay in opening the 1D valve until the 1 I valve is closed preventing pressurized power fluid being freely exhausted from the pump 226 to the reservoir 228 through the 1 CV control valve assembly. The opening movement of the 1 D sleeve valve results in responsive closing movement of the 3 D sleeve valve (the 2 D sleeve valve being already closed) via the common connection of the B actuator chambers between the 1D-b2 and 2D-b1 and 2D-b2 and 3D-b1 ports thereof (Fig.3) i.e. arrows 342 to 344 in Fig.9 A2, the closing movement of the 3D valve being readily permitted since its 3D-A actuator port is exhausted to the reservoir through the tanked conditioning valve C via lines 345, 346. Additionally, the opening of the 1D sleeve valve signals the opening of a 3-PR (precompression) valve of the 3CV control valve assembly, by exhausting the pressure on the pilot port 3-194 (Figs.3 and 5) from the differentially landed piston 190, 196 permitting the piston to be unseated at 193 by pressurized fluid constantly existing in the line 188 (connected to the power fluid inlet 74 i.e. from power circuit pump 210), whereby the 3-PR valve is opened, the sequence of the signal which permits this opening being such that initiation of the precompression stroke in the 3CV control valve assembly lags the beginning of the suction and discharge strokes in time, the opening of the 3-PR valve pressurizing the central chamber 82 of the 3-CV valve assembly via a restrictor 179 in the PR valve such as to effect precompression via the piston 44 of fluid in the triplex pump cylinder 24 associated with the 3-CV control valve. When pressure exists in any D-a1 line (Figs.3, 7 and 7A) the check valve C of the appropriate PO valve is inoperative and pilot pressure at its port 168 simply serves to open the PO valve to pressurize the A chamber of the appropriate D sleeve valve, however when the appropriate D-a1 line is depressurized, the pilot pressure at port 168 is exhausted to the reservoir 228 through the check valve C and via duct 176 to the de-pressurized line D-a1 of the exhausted A chamber of the associated closed I sleeve valve (Figs.3 and 9 A2). Thus from above and Fig. 9 A2 it can be seen that a pressurized A conditioning valve and tanked B and C conditioning valves provide simultaneous and responsive shifting of the 2 I and 1 I valves, shifting of the latter of which causes simultaneous shifting of the ID and 3D valves and conditions the 3PR valve, all as outlined above. Smooth operation is effected when the I and D valves are opened because as they near their lower open position, I-D and D-D ports pass pressurized fluid from the A chambers to the B chambers (Figs.4, 6 and 7) via inter-connecting ports I-Db and D-Db which together with a hydraulic cushion provided by dual 1-B and D-B passageways prevent abrupt stopping of the sleeve valves. Additionally the D ports supply make-up fluid to the B chambers when there is insufficient fluid in the common closing B chamber, such deficiency occurring when the pilot fluid that opens the PO valves is exhausted to the reservoir 228. To accomplish positioning of the I and D valves as described above and illustrated in Figs.9 A1 and 9 A2, the C valve is tanked and the A valve is pressurized by tripping of the cycling valve 1 FP (Figs.1 and 8) (which together with the other cycling valves 2 FP and 3 FP are normally biased to a closed position) via a cam actuator 58 of the 1-42 piston rod assembly on completion of the discharge stroke in the 1-40 power cylinder, which discharging function, completed in the immediately preceding phase of the cycle initiates the phase described and illustrated in Figs. 9 A1, 9 A2 and 9 A3, the opened 1FP valve at 362 passing pressurized fluid from the pump 226 to port 252 of the A valve which is thus placed in a pressurized condition and directs the pressure control fluid as described and shown in Fig. 9 A-2 whereby the C valve is moved to its tanked position, the B valve remaining unaffected by the tripped 1-FP valve and being in a tanked position. Thus the sleeve valves I and D are shifted ultimately in response to the actuation of the cycling  FP valves which furnish only the pilot pressure signal to the control circuit conditioning valves A, B and C which then furnish the pilot pressure signals to the appropriate sleeve valve pilot ports 2 I-A, I D-A etc, the control circuit conditioning valves A, B and C being prevented from drifting after shifting in response to tripping of the cycling valve by means of double cylinder lock valves DCL-A, DCL-B and DCL-C shown in Fig.8. 2nd PHASE OF PUMPING CYCLE:- In the 2nd phase of the pumping cycle the numbers 1-40, 2-40 and 3-40 power cylinder assemblies undergo precompression suction and discharge functions respectively as follows:- On completion of the discharge stroke in the 2-40 power cylinder in the 1st phase of the pumping cycle the 2 FP valve is tripped to pressurize i.e. supply control circuit fluid from the control circuit pump 226 to port 254 of the conditioning valve B which is thus shifted from the tanked position of the 1st phase to its pressurized position causing movement of the valve A to its tanked position, the valve C remaining unaffected i.e. still tanked during this 2nd phase of the pumping cycle. The pressurized valve B opens the 3-I sleeve valve to charge the 3-40 power cylinder via a central chamber 82 to effect the discharge function at the 3-22 fluid end (opening movement of the 3-I sleeve valve causing closing movement of the 2-I valve with subsequent opening of the 2-D valve and consequent closing of the I-D valve in a manner similar to that described above inthe 1st pumping phase), the fluid displaced by the rod end in this 3-40 cylinder passing through a common rod end passage 61 to cause the 2-